docs: def annual_cooling_design_day_004(self):
          """A design day object representing the annual 0.4% cooling design day."""
          if bool(self._summer_des_day_dict) is True:
              tau = None
              month_num = int(self._summer_des_day_dict['Month'])
              if self._monthly_tau_beam != [] and self._monthly_tau_diffuse != [] \
                  and self._monthly_tau_beam[month_num - 1] is not None and \
                      self._monthly_tau_diffuse[month_num - 1] is not None:
                          tau = (self._monthly_tau_beam[month_num - 1],
                                 self._monthly_tau_diffuse[month_num - 1])
              return DesignDay.from_ashrae_dict_cooling(
                  self._summer_des_day_dict, self.location, False,
                  self._stand_press_at_elev, tau)
          else:
              return None